Dissolution Thermodynamic Properties Research Articles

Solubility measurement, correlation, and thermodynamic analysis of ε-CL-20 in four binary solvents (ethyl acetate + halogenated hydrocarbon) from 288.15 to 328.15 K

In this work, the solubility of ε-CL-20 in four binary solvents composed of ethyl acetate and halogenated hydrocarbons (bromobenzene, chlorobenzene, dibromomethane, 1,1,2,2-tetrachloroethane) was measured over the temperature range of 288.15–328.15 K at 0.101 MPa by gravimetric method. Under similar conditions, the order of solubility of ε-CL-20 is ethyl acetate + bromobenzene ≈ ethyl acetate + chlorobenzene > ethyl acetate + dibromomethane > ethyl acetate + 1,1,2,2-tetrachloroethane and the solubility decreases with the increase of halogenated hydrocarbon content. The results also reveal that the solubility is negatively correlated with temperature when the mole fraction of halogenated hydrocarbons is low, otherwise the result is opposite. The modified Apelblat model, van’t Hoff model, CNIBS/R-K model, Jouyban-Acree model and Jouyban-Acree-van’t Hoff model were used to correlate the experimental solubility data and all of the models perform well. The modified Apelblat model and Jouyban-Acree-van’t Hoff model are relatively excellent. The dissolution thermodynamic properties of ε-CL-20 in four binary solvents were calculated and analyzed. The results show that the dissolution processes of ε-CL-20 are entropy-driven non-spontaneous processes. This work is significant to the design and optimization of the crystallization of ε-CL-20.

Impact of Temperature on the Solubility of Ionic Compounds in Water in Cameroon

Purpose: The aim of the study was to assess impact of temperature on the solubility of ionic compounds in water in Cameroon. Methodology: This study adopted a desk methodology. A desk study research design is commonly known as secondary data collection. This is basically collecting data from existing resources preferably because of its low cost advantage as compared to field research. Our current study looked into already published studies and reports as the data was easily accessed through online journals and libraries. Findings: The study found that the solubility of most ionic compounds increases with an increase in temperature. This is because higher temperatures provide more kinetic energy to the ions, helping them to break free from the crystal lattice and dissolve in water. For example, the solubility of salts like potassium nitrate (KNO3) significantly increases as the temperature rises, allowing more of the compound to dissolve. However, this trend is not universal for all ionic compounds. Some, such as calcium sulfate (CaSO4), exhibit a decrease in solubility with rising temperature. This anomaly can be attributed to the exothermic nature of the dissolution process for these compounds, where heat is released when they dissolve. As temperature increases, the equilibrium shifts to favor the solid form, reducing solubility. Therefore, while temperature generally enhances the solubility of ionic compounds in water, specific behaviors can vary depending on the individual compound's dissolution characteristics and thermodynamic properties. Implications to Theory, Practice and Policy: Le Chatelier’s principle, Arrhenius theory of dissociation and solubility product constant (KSP) theory may be used to anchor future studies on assessing impact of temperature on the solubility of ionic compounds in water in Cameroon. Practical applications of temperature-dependent solubility data should be integrated into industrial processes, particularly in fields such as pharmaceuticals, fertilizers, and desalination. Policymakers should consider incorporating temperature-dependent solubility data into environmental regulations, particularly concerning water pollution and waste management.

Insight into the solution thermodynamic properties of cimetidine form A and form B based on experiments and molecular simulations

Cimetidine (CIM) is an antagonist of the type II histamine receptors, and act as a significant agent in the treatment of stomach ulcers. In this work, the effect of polymorphism and solvent type on the thermodynamic properties of CIM was investigated based on experimental results and molecular simulations. The solubility data of two polymorphs for CIM (forms A and B) in organic solvents were measured and correlated with four thermodynamic models. It could be found that the solubility of CIM form A is higher compared to form B. In addition, molecular simulations were adopted to investigate the mechanism of the solubility and stability of the two forms. Hirshfeld surface analysis shows that strong H···N interaction contributes to better stability of form B. Meanwhile, molecular electrostatic potential surface and radial distribution function results indicate that the solubility behavior is significantly influenced by the intensity of the solute–solvent interactions. Finally, the dissolution thermodynamic properties, including the enthalpy change, the Gibbs energy change, and the entropy change, were calculated and the results show that the dissolution process of CIM is endothermic, entropy-driven and spontaneous.

Determination of Gibberellin A3 solubility in different solvents based on mathematical models, solvent effect and thermodynamic analysis

For gibberellin A3, one of the important phytohormones, solubility parameters and characterisation are the basis of data for its isolation and purification. In this work, the solubility of GA3 was determined in twelve pure solvents (ethanol, isopropanol, 1-butanol, n-hexane, n-heptane, trichloromethane, ethyl acetate, acetone, xylene, tetrahydrofuran, dimethylsulfoxide and acetonitrile) and three binary mixed solvents (trichloromethane + ethanol, acetonitrile + ethanol and n-hexane + ethanol) at temperatures ranging from 278.15 K to 323.15 K. The experimental results showed that the solubility of GA3 in various solvents was positively correlated with the temperature, with better solubility in ethanol. The measured data were fitted with the modified Apelblat model, the Buchowski-Ksiazaczak λh model, the CNIBS/R-K model and the Jouyban-Acree model. Then, the solvent effect was analyzed using the KAT-LSER model, which showed that the dipole polarisation rate of the solvent had the greatest effect on the solubility of GA3. In addition, the dissolution thermodynamic properties of GA3 were studied with the van't-Hoff equation, concluding that the dissolution of GA3 was an entropy-driven heat absorption process. The data obtained from this research will contribute to improve the purity of GA3 in the recrystallisation process, and ensure its efficacy and stability, thereby playing a certain guiding role in the industrial production of GA3.

Solubility measurements, correlation, and thermodynamic characterization of 4-guanidinobenzoic acid hydrochloride in pure and binary solvents from 294.55 K to 333.65 K

The solubility of 4-guanidinobenzoic acid hydrochloride (4-GABCL) in pure solvents (H2O, methanol, ethanol, n-propanol, isopropanol, 1-butanol, and 1-pentanol) and two binary solvents (H2O + ethanol/isopropanol) were determined by the dynamic saturation method in the temperature range of 294.55 K–333.65 K under atmospheric pressure. From the measurement results, it could be observed that the solubility of 4-GABCL in both pure and binary solvents all increased with increasing temperature. The solubility order of 4-GABCL in pure solvents was ranked as follows: methanol > H2O > n-propanol > ethanol > n-butanol > isopropanol > n-pentanol. The solubility of 4-GABCL in binary solvents tended to increase and then decrease with increasing molar fractions of ethanol and isopropanol, and the solubility of the solute in the binary solvents was greater than that of each in the monosolvents. In addition, Ideal model, Apelblat model, λh model, Wilson model, and NRTL model had been used to correlate the solubility of 4-GABCL in pure and binary solvents. Correlated effects show that the Wilson model gives the best correlation. The influence of solvents on the solubility of 4-GABCL was further studied by KAT-LSER model. The results showed that the solubility was mainly affected by the polarizability and the self-viscosity of the solvent.The mixing and dissolution thermodynamic properties of 4-GABCL in all experimental solvents had been calculated and analyzed by using the Wilson equation and solvent data. It was determined that the mixing and dissolution of 4-GABCL were spontaneous, endothermic and entropy-driven in the study systems. Besides, the solubility order of the pure solvent is consistent with the dissolution entropy at a temperature of 318.15 k.

Uncovering dissolution behavior and thermodynamic properties of metronidazole benzoate in twelve mono-solvents by experiments and molecular simulation

In this study, metronidazole benzoate (MBZ), a nitroimidazole antibiotic, was selected to measure the solubility in 12 solvents by the gravimetric method in the temperature range of 278.15 K to 323.15 K. The intermolecular interactions dominated by H···H and O···H contacts in the solid phase were determined using Hirshfeld surface analysis (HS). Subsequently, molecular simulations involving molecular electrostatic potential surface (MEPs), hydrogen binding energy (EHB) and mean square displacement (MSD) revealed the effect of the solvent polarity, hydrogen bonding and diffusion process on the dissolution behavior of MBZ. Furthermore, six thermodynamic models, all with values of ARDs less than 5 %, were successfully correlated with the experimental solubility results. The Apelblat model achieved the best fitting. Based on the NRTL models, relevant thermodynamic parameters were obtained, indicating that the dissolution process of MBZ in various solvents is spontaneous and entropy-driven. In the measured temperature range, the solubility of MBZ in different solvents increased from 4-times to 25-times as the temperature changed, which provided an important theoretical basis for the industrial production of MBZ.

Study on 2-amino-4-chloro-6-methoxypyrimidine in four binary solvent mixtures: Solubility measurement, calculation, preferential solvation and extended Hildebrand solubility parameter approach analysis

Equilibrium mole fraction solubility of 2-amino-4-chloro-6-methoxypyrimidine in methanol/ethanol/acetone/N,N-Dimethylformamide (DMF) plus water was experimentally measured by isothermal saturation method at 278.15–323.15 K under 101.2 kPa. The mixed solvents with low moisture and high temperature played a supportive role in the dissolution of 2-amino-4-chloro-6-methoxypyrimidine. The amount of 2-amino-4-chloro-6-methoxypyrimidine dissolved in DMF + water was more than that in other three systems and the ranges of values for the solubility (mole fraction) of 2-amino-4-chloro-6-methoxypyrimidine in methanol/ethanol/acetone/DMF + water were 0.0002046–0.009616, 0.0002046–0.01060, 0.0002046–0.04918 and 0.0002046–0.1197, respectively. The Jouyban-Acree (JA), Apelblat-Jouyban-Acree (AJA) and van’t Hoff-Jouyban-Acree (VJA) model were applied to calculate the solubility data of 2-amino-4-chloro-6-methoxypyrimidine in mixtures. The preferential solvation parameter δx1,3 > 0 in 0.32 < xmethanol < 1, 0.24 < xethanol < 1, 0.21 < xacetone < 1 and 0.19 < xDMF < 1, the 2-amino-4-chloro-6-methoxypyrimidine was preferentially dissolved by cosolvents and the 2-amino-4-chloro-6-methoxypyrimidine was dissolved preferentially by water within δx1,3 < 0. What’s more, the interaction between solute - solvent molecules and the internal interaction of molecules was analyzed by extend Hildebrand solubility approach (EHSA) and in the concentration range with W > δ1+2δ3, the hydrophobic groups in the 2-amino-4-chloro-6-methoxypyrimidine played a dominant role, while in other ranges self associations of solute, solvent or both were observed. The dissolution thermodynamic properties were obtained by van’t Hoff plots and the ranges of values for ΔsolHo (kJ∙mol−1)/ ΔsolGo (kJ∙mol−1)/ ΔsolSo (J∙mol−1) were 9.74 – 31.12, −17.84 – 4.96 and 33.79 – 161.89.

Solid-liquid equilibrium of glucosamine hydrochloride in four binary solvents: Experiments, modeling, and molecular simulation

Glucosamine hydrochloride (GAH) is a marine biological preparation derived from natural chitin and improves articular cartilage metabolism. In this study, the solubility of GAH in four binary solvents (water + methanol, water + ethanol, water + isopropanol, and water + acetone) was gravimetrically determined over the temperature range of 283.15 K to 323.15 K. The solubility of GAH were found increasing monotonically with water content and temperature. In alcohol mixtures, the solubility of GAH can be ranked as: (water + methanol) > (water + ethanol) > (water + isopropanol). Four thermodynamic models (the modified Apelblat equation, van't Hoff equation, (CNIBS)/R-K model and Jouyban-Acree model) were used to correlate the experimental solubility data, which the (CNIBS)/R-K model showed the best fitting performance. The dissolution thermodynamic properties of GAH were also calculated. The results indicate that the dissolution process is driven by both entropy and enthalpy. To explore the solid–liquid equilibrium behavior from molecular level, the Hirshfeld surface of GAH crystal was generated and molecular dynamics simulations of mixed systems were performed. Based on equilibrium configurations of different mixtures, molecular interactions between solvent–solvent and solute–solvent were calculated. Meanwhile, the simulation snapshots and radial distribution function plots were analyzed to interpret association of solvents.

Solubility and Thermodynamic Modeling of 5-Nitrofurazone in Pure Solvents and Binary Solvent Mixtures

In this work, the solubility of 5-nitrofurazone (Form α) in 10 pure solvents (water, methanol, ethanol, acetonitrile, ethyl acetate, n-propanol, isopropanol, acetone, formamide, N,N-dimethylformamide) and two binary mixed solvents (N,N-dimethylformamide + water, N,N-dimethylformamide + acetonitrile) were measured by ultraviolet–visible spectrophotometry from 278.15 to 313.15 K. The experimental results showed that the solubility of 5-nitrofurazone (Form α) in all pure solvents and binary mixed solvents was positively correlated with temperature. Additionally, the modified Apelblat equation, the λh equation, and the nonrandom two-liquid (NRTL) model were used to correlate the experimental solubility results. The results showed that all of these models could correlate the experimental data well, and the modified Apelblat equation provided the best fitting results. Finally, the mixing and dissolution thermodynamic properties of 5-nitrofurazone (Form α) in 10 pure solvents and two binary solvents, including enthalpy, entropy, and Gibbs energy, were calculated by experimental results and the NRTL model.

Solid-liquid equilibrium and dissolution thermodynamic properties of L-isoleucine in binary solvent mixtures

Thermodynamic properties, which play an important role in design and optimization of crystallization processes, are the essential data for the study of crystal nucleation and growth. In this study, the solubility of L-isoleucine were firstly determined by gravimetric method in three binary solvent mixtures including water + (ethanol, acetonitrile or DMSO) in the temperature range of 303.20 K to 338.05 K at atmospheric pressure. The effects of temperatures and solvent types on the dissolution process of L-isoleucine were investigated. It was found that the solubility of L-isoleucine increased dramatically with the increasing of the mole fraction of water in each binary solvent mixture and increased monotonically with the increasing of temperature. To extend the applicability of the solubility data, the experimental solubility data of L-isoleucine were fitted and analyzed using the modified Apelblat equation, the CNIBS/R-K model and the Jouyban-Acree model. Finally, based on the Van’t Hoff equation and the experimental solubility data, the apparent dissolution thermodynamic properties of L-isoleucine including apparent dissolution enthalpy, apparent dissolution entropy, and apparent Gibbs free energy change of dissolution process were calculated and discussed.

Diffusion Coefficient and Absorption of Carbonyl Sulfide in 1-Hexyl-3-methylimidazolium Bis (Trifluoromethyl) Sulfonylimide ([hmim][Tf2N

The solubility of carbonyl sulfide (COS) and also the diffusion coefficients of COS, carbon dioxide, and hydrogen sulfide were experimentally investigated in 1-hexyl-3-methylimidazolium bis(trifluoromethyl) sulfonylimide ([hmim][Tf2N]). The solubility was measured using a static apparatus, and the acid gas diffusivity was obtained by monitoring pressure drop with low initial pressure via the so-called semi-infinite volume method. All experimental absorption trials were carried out in the range of low and medium pressures and temperatures from (313.15 to 353.15) K. Furthermore, all diffusion coefficient experiments were determined at a temperature from (313.15 to 333.15) K and low pressure to some extent to be acceptable in the semi-infinite volume approach. The experimental results were correlated using the Shiflett and Yokozeki versions of the Redlich–Kwong equation of state. In addition, Henry’s law constants and the thermodynamic properties of dissolution at infinite dilution were calculated and discussed.

Solid-liquid phase equilibrium and thermodynamic properties analysis of paliperidone palmitate in 21 kinds of mono-solvents

Solid-liquid equilibrium solubility paliperidone palmitate (PP) in 21 kinds of mono-solvents, including ethanol, n-propanol, i-propanol, n-butanol, i-butanol, s-butanol, n-pentanol, i-pentanol, 2-butanone, methyl isobutyl ketone, cyclohexanone, ethyl formate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, amyl acetate, N,N-dimethylformamide (DMF), tetrahydrofuran (THF), toluene, and 1,4‑dioxane were determined by a gravimetric method at a various temperature. The solubility of PP increases with the increase of temperature. In alcoholic solvents, the solubility order is: n-pentanol > i-pentanol > i-butanol > s-butanol > n-butanol > n-propanol > i-propanol > ethanol. In easter solvents, the solubility of PP ranking as: ethyl formate > amyl acetate > butyl acetate > propyl acetate > ethyl acetate > isopropyl acetate. For ketone solvent, the solubility order is: cyclohexanone > 2-butanone > methyl isobutyl ketone. In other solvents, the solubility order is: THF > toluene > 1,4‑dioxane > DMF. The maximum solubility of PP is 0.1922 mol·mol−1 (toluene, 353.15 K), and the minimum solubility is 0.0003788 mol·mol−1 (ethanol, 318.15 K). Four thermodynamic models, i.e., the modified Apelblat model, the Yaws model, the NRTL model and the Wilson model were selected to correlate the solubility data in this paper. NRTL model fits best among all the models with RAD no larger 4.84 × 10−2 (n-propanol) and RMSD value less than 12.55 × 10−4 (1,4-dioxane). Furthermore, dissolution thermodynamic properties of PP were evaluated based on the Wilson model. The dissolution process of PP is demonstrated to be spontaneous in the chosen organic solvents.

Solubilities of 3, 3, 3-trifluoropropene in pentaerythritol tetrahexanoate and pentaerythritol tetraoctanoate from 278.15 K to 343.15 K at pressures to 1 MPa

Due to the very low GWP and good thermodynamic properties, 3, 3, 3-trifluoropropene (R1243zf) was considered as a promising substitute for R134a. The phase behavior of R1243zf with lubricant oils is essential for the optimization of the refrigeration cycle. In this work, the solubility of R1243zf in pentaerythritol tetrahexanoate (PEC6) and pentaerythritol tetraoctanoate (PEC8), which are the two pure components of polyol ester (POE) oil, was determined at temperatures from 278.15 K to 343.15 K and pressures up to 1.0 MPa using isochoric saturation method. The experimental data were regressed by means of non-random two liquid (NRTL) model and Krichevsky-Kasarnovsky (K-K) model, respectively. Both of the two models present good correlation results with the absolute average relative deviations lower than 3.0 %. Moreover, the solubilities of different hydrofluoroolefin refrigerants (R1234yf, R1234ze(E) and R1243zf) in the studied PECs were compared. Results show that the molar fraction of HFOs dissolved in the same PECs follows: R1234ze(E) > R1243zf > R1234yf. In addition, the dissolution thermodynamic properties including the mixing enthalpy, mixing Gibbs energy and mixing entropy of R1243zf in PEC6 and PEC8 were calculated according to experimental solubility data and the NRTL model, and the dissolution process was analyzed.

Solubility measurement, correlation and thermodynamic properties of 2,3,4-trichloro-1,5-dinitrobenzene in fifteen mono-solvents at temperatures from 278.15 to 323.15 K

The solubility of 2,3,4-trichloro-1,5-dinitrobenzene (TCDNB) was measured by a laser dynamic method over the temperature range from 278.15 K to 323.15 K under 0.1 MPa in fifteen mono-solvents (methanol, ethanol, isopropanol, n-butanol, toluene, dichloromethane, chloroform, tetrachloromethane, 1,2-dichloroethane, acetone, ethyl acetate, acetonitrile, N-methylpyrrolidone (NMP), N,N-dimethylformamide dimethyl sulfoxide (DMF), dimethyl sulfoxide (DMSO). The solubility of TCDNB could be increased with increasing temperature in fifteen mono-solvents. TCDNB solubility is in the following order at 298.15 K: NMP>DMF>DMSO>toluene>acetone>ethyl acetate>dichloromethane>1,2-dichloroethane>chloroform>acetonitrile>tetrachloromethane>methanol>ethanol>n-butanol>isopropanol. The KAT-LSER model was used to investigate the solvent effect, which revealed that the hydrogen bond acidity of solvents has a greater effect on TCDNB solubility. The van't Hoff model, the modified Apelblat model, the λh model, and the non-random two liquid (NRTL) model were used to correlate the solubility of TCDNB. The calculated solubility data agreed well with the experimental data, and the modified Apelblat model fit best. Furthermore, the van't Hoff and Gibbs equations were also used to calculate the dissolution thermodynamic properties of TCDNB in various solvents. TCDNB dissolution could be an enthalpy-driven, non-spontaneous, and endothermic process in fifteen mono-solvents. The determination and fitting solubility of TCDNB, as well as the calculation of its thermodynamic properties, would be critical in the purification and crystallization of its preparation process research.

Solubility, dissolution properties and molecular dynamic simulation of 2,6-bis(picrylamino)-3,5-dinitropyridine in pure and binary solvents

The solubility of energetic materials in organic solvents plays a critical role in industrial manufacturing. Here, thermodynamic analysis and molecular simulation were used to investigate the solubility of 2,6-bis(picrylamino)-3,5-dinitropyridine (PYX), which is a widely used heat-resistant explosive. Solubility data in five pure solvents and four binary solvents were collected from 293.1 K to 353.1 K using a gravimetric method. The results show that the solubility data has a positive correlation with temperature and solvent composition in all selected solvent systems, except for the cosolvency phenomenon that occurs in the (DMSO + ethyl acetate) mixture. The modified Apelblat equation, the λh equation and two local composition models (Wilson and NRTL model) were used to correlate the experimental solubility data and the modified Apelblat equation achieves the best fitting performance (at a constant solvent composition when fitting the binary solvents). In addition, the solvation free energy calculated from molecular dynamic simulation revealed that the rank of solute–solvent interactions follows the same tend as solubility. Radial distribution function (RDF) further confirmed that solvent–solvent interactions are also important in determining the solubility behavior. Finally, the dissolution thermodynamic properties, including dissolution Gibbs energy, dissolution enthalpy and dissolution entropy of PYX in all the tested solvent systems were calculated and analyzed based on the NRTL model, which suggests that the dissolution process of PYX is spontaneous.

The dissolution behavior and thermodynamic properties analysis of pentoxyverine citrate in aqueous solutions of alcohols

The objective of this work is to study the dissolution behavior and thermodynamic properties of pentoxyverine citrate in aqueous solutions of alcohols. The results of solubility data at temperature range from 278.15 K to 318.15 K were obtained by the isothermal equilibrium method under atmospheric condition. In pure solvents, the largest solubility data in mole fraction is found in water at 318.15 K (2.756 × 10−2), followed by ethanol (1.156 × 10−2), n-propanol (8.129 × 10−3), isobutanol (5.233 × 10−3), isopropanol (4.340 × 10−3) and 1-butanol (3.435 × 10−3). The order of solubility from large to small is consistent with the order of solvent polarity. The solubility profile in mixtures of (ethanol + water), (n-propanol + water) and (isopropanol + water) increases firstly and then decreases with the increasing mass fraction of alcohols at all studied temperatures, and it reaches a maximum at w = 0.60 (the mass fraction of ethanol) in mixtures of (ethanol + water) at all investigated temperatures, for two other binary mixtures, the mass fraction of n-propanol and isopropanol is 0.40. The analysis of extended Hildebrand solubility approach indicate the solvent–solvent interactions and specific interactions are unfavorable for the dissolution process. The values of relative average deviation (RAD) for crystalline pentoverine citrate demonstrated well correlation of solubility values with Apelblat equation and Jouyban-Acree model. The positive values of ΔHsolo and ΔSsolo for dissolution behavior indicate the dissolution process was not only endothermic but also entropic-favouring. Moreover, the enthalpy is the main contributing force to the Gibbs free energy during the dissolution of pentoverine citrate.

Revealing dissolution behavior and thermodynamic properties of tinidazole in 12 mono-solvents based on experiments and molecular simulation

The crystal structure and thermodynamic properties of Tinidazole (TNZ), an antiprotozoal and antibacterial drug, were investigated in the solid phase and liquid phase. The solubility of TNZ in 12 solvents was also measured in detail by the gravimetric method in the temperature range from 288.15 K to 328.15 K. The intermolecular interaction was confirmed by Hirshfeld surface analysis, demonstrating that H···H and O···H contacts were decisive in the solid-state structure. Furthermore, the statistical correlations results of the heatmap indicated that the solubility of TNZ in the liquid phase was related to the aspects in terms of solvent–solute intermolecular interactions and solvent properties. Following that, the molecular simulations involving molecular polarity Index (MPI), molecular electrostatic potential surface (MEPs), hydrogen binding energy (EHB) and mean square displacement (MSD) were applied successfully to the interpretation of the effect of polarity, hydrogen bond formation and diffusion, to better understand the dissolution behavior of TNZ in 12 solvents. More importantly, five thermodynamic models were used to examine the solubility data as the ARD% values were all less than 7 %. Subsequently, based on the NRTL model, the related thermodynamic parameters were obtained, showing that the dissolution process of TNZ in various solvents was spontaneous and entropy-driven. Through experiments and molecular simulation, these results can provide an important theoretical basis for the industrial production of TNZ.

Solubility determination and mixing thermodynamic properties of R1243zf in two 1-butyl-3-methyl-imidazolium based ionic liquids

3,3,3-Trifluoropropene (R1243zf), as a new-type hydrofluoro-olefin refrigerant with extremely low GWP and thermophysical properties similar to R134a, has received more and more attention. Ionic liquids (ILs) with 1-butyl-3-methyl-imidazolium ([BMIM]+) cation are a promising kind of absorbent in absorption refrigeration cycle (ARC) owing to their low viscosity level and good stability. Towards better understanding the phase behavior of R1243zf/[BMIM]+ IL mixtures and promoting their application in ARC, the solubilities of R1243zf in [BMIM][TFO] and [BMIM][PF6] were experimentally determined using isochoric saturation method in this work. The non-random two liquid (NRTL) and Krichevsky-Kasarnovsky (K-K) model were utilized to correlate the experimental data, and both models exhibited reasonable results. In addition, the dissolution thermodynamic properties (enthalpy, entropy and Gibbs energy) and Henry’s law constants of R1243zf in the two ILs were calculated, and the variation with solubility was analyzed. Furthermore, the absorption capacities of [BMIM][TFO] and [BMIM][PF6] to different refrigerants were compared based on the reported data in the literatures.

Dissolution thermodynamic properties calculation and intermolecular interaction analysis of diacerein in different pure and mixed solvents

The purpose of the present work is to improve the solubility of insoluble diacerein with cosolvent. The solubility of diacerein in pure polar aprotic solvent is significantly higher than that in other solvents. In mixtures of ethyl acetate + isopropanol, the solubility of diacerein increases firstly and then decreases with the addition of cosolvent at a certain temperature. However, in N, N-dimethylacetamide (DMAC) + water systems, the solubility and DMAC concentration shows a monotonic increasing trend at a given temperature. Multiple linear regression analysis of various solvent property parameters indicates that hydrogen bonding and the enhancement of solvent polarity are helpful to the dissolution of diacerein. The calculation results of preferential solvation show that diacerein molecules are preferentially solvated by isopropanol and water in isopropanol / water-rich mixtures. In the DMAC-rich region, solute are preferentially solvated by DMAC, while in the ethyl acetate + isopropanol system, with the increase of ethyl acetate concentration, the solute is solvated firstly by cosolvent and then solvated by isopropanol again. The calculation of apparent thermodynamic properties indicates that the dissolution process is an endothermic and entropy driven process.

Investigation on Hansen solubility parameter, solvent effect and thermodynamic properties of 3-methylflavone-8-carboxylic acid dissolved in different solvents

In this work, the dissolution behavior of a novel pharmacological factor, 3-methylflavone-8-carboxylic acid (MFCA) in different solvents was studied. Firstly, the solubility of MFCA in ten mono-solvents (acetonitrile, tetrahydrofuran, acetone, N,N-dimethylformamide, methyl acetate, ethyl acetate, butyl acetate, methanol, ethanol and isobutanol) and three binary solvents (N,N-dimethylformamide + acetonitrile, tetrahydrofuran + acetonitrile, methyl acetate + acetonitrile) at different temperatures (273.15–323.15 K) was determined by static equilibrium-high performance liquid chromatography. The experimental results showed that the solubility of MFCA increased with increasing temperature in tested solvents, and the solubility of MFCA in N,N-dimethylformamide was maximal. The Hansen solubility parameter was used to research the dissolution behavior of MFCA. Meanwhile, the solvent effect was discussed by KAT-LSER model in ten mono-solvents, and it was found that the hydrogen bond basicity and nonspecific dipolarity/polarizability were favorable to the dissolution of MFCA. In addition, modified Apelblat model, λh model, CNIBS/R-K model and Jouyban-Acree model were used to analyze the correlation and evaluate the applicability for the experimental solubility data of MFCA. The calculated data showed that modified Apelblat model and CNIBS/R-K model are the best models for mono and binary solvents, respectively. Finally, the dissolution thermodynamic properties of MFCA were studied by van't Hoff analysis, indicating that the dissolution of MFCA was an endothermic and entropic driven process. To sum up, these experimental results could provide pretty reference for purification and crystallization optimization of MFCA, and realize the industrial large-scale production of various drugs such as diuretic.